Download 01431-02.3 Plant Growth

Course:
Unit 2:
01.431
Agriculture Crop Production and
Management
Plant Physiology
Lesson 3:
Plant Growth
QCC: ........................................................................................................................343, 349, 352
Objectives:
1.
2.
3.
4.
5.
Explain how plants grow.
Describe the role of plant hormones.
Explain photosynthesis.
Categorize the nutrient needs of plants.
Identify signs of nutrient deficiencies.
Teaching Time:
3 hours
References:
Biondo, Ronald J. & Jasper S. Lee. Introduction to Plant and Soil Science and
Technology. Interstate Publishers, Inc. Danville, IL 1997.
Biondo, Ronald J. Activity Manual Introduction to Plant and Soil Science and
Technology. Interstate Publishers, Inc. Danville, IL. 1998.
Teacher=s manual to text
Materials and Equipment:
Microscope
Prepared slides
Appropriate plants
Greenhouse, etc.
Pea seeds
Overhead projector
Transparencies 2.3.1 - 2.3.3
Course: 01.431 Agricultural Crop Production and Management
Revised August 1999
Unit 2, Lesson 3
1
Georgia Agriculture Education Curriculum
TEACHING PROCEDURE
Introduction and Mental Set
Show students two plants of differing size and the same age. Ask students
how could that be? genetics, nutrition, environment
Discussion
1.
Plant a few pea seeds in a growing medium and have students
make observations of the peas as they germinate for a few days.
2.
How do plants grow.
A.
Starts at the cellular level
B.
Plant cells are organized into tissues that perform specialized
functions
C.
Tissues are organized into organs (roots, stems, leaves and
reproductive parts)
D.
All photosynthesis, growth, and development are controlled by
genetic material, which are located in chromosomes.
E.
Life processes are regulated by hormones which are produced
in cells.
F.
The parts of a cell include: Display and Discuss transparency
2.3.1
$ Nucleus- controls cell actions. This is the command center.
Contains DNA.
$ Vacuole- Large sac that contains water, stored foods, salts,
pigments, and wastes.
$ Mitochondria and chloroplasts- Chloroplasts are
contained within the Mitochondria and contain green
pigments called chlorophyll that trap light for
photosynthesis. These chloroplasts give plants their green
color. The Mitochondria converts food into energy through
cellular respiration.
$ Endoplasmic reticulum and golgi bodies- Endoplasmic
reticulum is the site for lipid(fats) and hormone production.
Proteins are processed, sorted, or modified in the golgi
body.
$ Cell wall made of cellulose. Cellulose is a complex sugar
molecule. After the cell stops growing the wall thickens
and becomes rigid. The paper industry uses cellulose in
the making of paper.
Course: 01.431 Agricultural Crop Production and Management
Revised August 1999
Unit 2, Lesson 3
2
Georgia Agriculture Education Curriculum
G.
H.
I.
J.
K.
Cell division- Increases the number of cells. Two types
$
Meiosis - Cells divide twice. Each offspring differs genetically
from all others. Produces new offspring.
$
Mitosis - A cell multiplies, inheriting the same chromosomes
and genetic material as the one it comes from. No
differentiation.
Cell elongation- Cells must elongate and enlarge so that a plant can
grow in size.
Cell differentiation- Allows cells to take on specific functions
depending on where they are in the plant. (Cells in the leaves may
take on the function of producing food.)
Meristem tissue- Located behind the root cap. The root cap is a layer
of cells that serve as protection for the meristem as the root grows
through the soil. As the cell elongates the pressure pushes the root
through the soil.
There are two types of growth that takes place in plants.
$
Primary plant growth - occurs in areas called apical
meristems which is located at the tips of roots and at the end of
stems. This is were unspecialized cells capable of division
through mitosis are found. The meristematic tissue of the shoot
contains immature buds and leaves. As the cells elongate the
leaves form.
$
Secondary plant growth - occurs only in woody plants. Takes
the place in the cambium. Causes an increased thickness of a
plant. It involves cell division in layers ringing the stem that
results in an increase in the width of the stem or trunk of the
plant. As the cells in the cambium divide they either become
xylem or phloem. Xylem forms to the inside and Phloem to the
outside.
3.
Distribute handouts 2.3.2 and 2.3.3, ARoot Development@ AShoot
Apical Meristem@.
4.
Allow students to use a microscope to see actual plant cells.
(Onion skins cut very thin will show cells very well.)
5.
Ask students how this coincides with their observations of the
pea growth.
6.
What are the roles of plant hormones?
A.
Plant hormones affect all aspects of a plants growth. They are
produced in one part of the plant and then transported to where
they regulate plant processes.
B.
There are 5 different hormones produced in plants:
$ Auxins - Produced in apical meristem. Cause cells to
Course: 01.431 Agricultural Crop Production and Management
Revised August 1999
Unit 2, Lesson 3
3
Georgia Agriculture Education Curriculum
$
$
$
$
elongate. They are responsible for phototrophic responses.
(The ability of a plant to bend towards light)
Gibberellins - Produced in stem and root apical meristems,
in seed embryos, and young leaves. Induce stem cell
elongation and cell division. Stimulate the development of
flowers and cause and increase in size to treated plants.
Cytokinins - responsible to cell division and differentiation.
Delays the aging process. Must be added to tissue culture
media for cell division to occur when trying to culture plant
tissue.
Ethylene - colorless gas produced in the nodes of stems,
ripening fruits and dying leaves. Ripening fruit produces
ethylene, which triggers the production of more ethylene,
speeding the ripening process. Cut flowers are never stored
with ripe fruit or decaying leaves because they may give off
ethylene and shorten the flowers life.
Abscisic Acid - Most apparent when a plant is under
stress. Causes stomata to close during periods of drought
so as to reduce water loss. Largely responsible for seed
dormancy and the loss of leaves by deciduous plants in the
fall.
7.
What is photosynthesis?
A.
The plant takes in carbon dioxide and water and in the
presence of sunlight the chlorophyl in the leaf manufactures
carbohydrates and releases oxygen in the air.
B.
Is the most important chemical reaction on earth.
C.
Chloroplasts are the Afactories@ where this reaction takes
place.
D.
Water absorbed by roots and carbon dioxide, which enter
through stomata, are used to make food.
E.
The food is produced in the form of sugar (glucose).
F.
This production of glucose by the plant causes by products in
the form of oxygen and water.
G.
The chemical equation is:
6 (CO2) + 12 (H2O) ---- C6H12O6 + (6) O2 + (6) H2O
Carbon + Water
----- Sugar + Oxygen + Water
Dioxide
8.
What are the nutrient needs of plants?
Two types of nutrients:
A.
Macronutrients- Nitrogen, Phosphorus, Potassium, Calcium,
Magnesium, Sulfur.
B.
Micronutrients- Boron, Copper, Chlorine, Iron, Manganese,
Molybdenum, Zinc
Course: 01.431 Agricultural Crop Production and Management
Revised August 1999
Unit 2, Lesson 3
4
Georgia Agriculture Education Curriculum
Nutrient
Function
Sign of Deficiency
Nitrogen
gives plants dark green color, produces
stem and leaf growth
yellow leaves, entire plant lighter
green, slow or dwarfed growth
Phosphorus
stimulates root development and
growth, improves winter hardiness
purplish coloration to leaves and
stems, stunted growth
Potassium
increases plant vigor and disease
resistance, thickens cell walls
yellowing or death of tissues at
tips and outer edges of older
leaves
Calcium
maintains strength of cell walls,
promotes early root growth
short much branched roots,
young leaves at growing points
die back
Magnesium
essential for chlorophyll and photo
synthesis
loss of green leaf color starting
with bottom leaves
Sulfur
Stimulates root growth, needed for
protein formation
young leaves light green with
veins being lighter
Boron
essential for pollination and
reproduction
young leaves yellow and thick
Copper
regulates several chemical processes
yellowing leaves, younger
leaves affected first
Chlorine
involved in photosynthesis
symptoms have not been
recognized
Iron
important in chlorophyll formation
young leaves yellow first, veins
remain green
Manganese
part of enzymes involved in respiration
and nitrogen metabolism
young leaves yellow first, veins
remain green
Zinc
part on enzymes involved in respiration
older leaves yellow, stunted
growth
Molybdenum
part of the enzymes involved in nitrogen
metabolism
older leaves yellow, stunted
growth
Course: 01.431 Agricultural Crop Production and Management
Revised August 1999
Unit 2, Lesson 3
5
Georgia Agriculture Education Curriculum
SUMMARY
Plant growth and development begins at the cellular level. There are
two types of cell division: meiosis and mitosis. Life processes in
plants are regulated by hormones produced in the cells. Essential
elements are needed for plant growth.
Evaluation
Written test
Lab activity
Course: 01.431 Agricultural Crop Production and Management
Revised August 1999
Unit 2, Lesson 3
6
Georgia Agriculture Education Curriculum
2.3.1
ORGANELLES ARE SPECIALIZED STRUCTURES IN A CELL.
2.3.2
Course: 01.431 Agricultural Crop Production and Management
Revised August 1999
Unit 2, Lesson 3
7
Georgia Agriculture Education Curriculum
THE SHOOT APICAL MERISTEM PRODUCES INCREASED LENGTH OF
THE STEM.
Course: 01.431 Agricultural Crop Production and Management
Revised August 1999
Unit 2, Lesson 3
8
Georgia Agriculture Education Curriculum
2.3.3
CELL DIVISION, ELONGATION, AND DIFFERENTIATION TAKE PLACE
IN THE ROOT APICAL MERISTEM.
Course: 01.431 Agricultural Crop Production and Management
Revised August 1999
Unit 2, Lesson 3
9